Niobium filter v. an aluminum filter.
Stirling
G C
GC
Holloway
A F
AF
D000535:Aluminum; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D009556:Niobium; D011829:Radiation Dosage; D011861:Radiography, Dental / Q000295:instrumentation*
D009556:Niobium; D000535:Aluminum